Thomson Effect

Thomson effect is related to the emf that develops between two parts of the single metal when they are at different temperature

Thus thomson effect is the absorption or evolution of heat along a conductor when current passes through it when one end of the conductor is hot and another is cold

If two parts of the metal are at small temperature difference dT ,themn the electric potential difference is proportional to dT dV α dT
or
dV=σdT
where σ is the constant of proportinality and is known as thomson coefficent

Peltier coefficent and thomson coeficent are related to thermopower according to following relations
π=Ts=T(dE/dT)
and σ =-T(ds/dT)=-T(d²E/dT²)

We have seen that all the three effects are defined in terms of three coefficent namely seaback,peltier and thomson coefficent but the basic quantity is thermo-power which is the rate of change of thermo-emf with temperature